TioCem is a specialized
cement
A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mi ...
with
photocatalytic features, used on the surface of buildings to reduce air pollution caused by exposure of the cement to
ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ...
light (UV).
Technology
Photocatalysis is initiated by
titanium dioxide
Titanium dioxide, also known as titanium(IV) oxide or titania , is the inorganic compound with the chemical formula . When used as a pigment, it is called titanium white, Pigment White 6 (PW6), or CI 77891. It is a white solid that is insolub ...
(TiO
2), which is added during the cement's production. Typical properties (i.e. strength) of cement applications (such as concrete) will be added to clean the air around the photocatalytic surface.
Nitrogen dioxide
Nitrogen dioxide is a chemical compound with the formula . It is one of several nitrogen oxides. is an intermediate in the industrial synthesis of nitric acid, millions of tons of which are produced each year for use primarily in the productio ...
(NO
2) will be particularly abated when daylight activates the photocatalytic surfaces.
The chemical process may be summarized as follows:
*Titanium dioxide (TiO
2) absorbs energy (UV radiation) and excites
electron
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no ...
s (e-)
TiO
2 + hν -> TiO
2 + h+ + e-
*Oxygen existing in the air (O
2) reacts with electrons (e-), generating super-oxide ions (O
2-)
*Super-oxide ions (O
2-) react with hydrogen ions (H+), generating the reactive
hydroxyl
In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydro ...
radicals (OH•)
H
2O + h+ -> H+ + OH-
*Nitrogen dioxide (NO
2) reacts with the pollutant remover (OH•) and generates nitrate (NO
3-), which reacts with the cement surface and is dissolved by water.
Using materials like TioCem, the abatement of NO
2 could be measured by a test method using the Italian standard UNI 11247, which is being discussed as the basis of a European standard. This method involves test apparatus in which a mixture of air and pollutant flows in a chamber over a test object; the pollutant burden is measured with (and without) exposure to light.
[Bolte, G. (2009): Innovative building materials - reduction of pollutants with TioCem, ZKG international No. 1-2009, (Volume 62), 63-70]
/ref> A defined level of NO2 abatement is guaranteed by the label “TX Active” (plus an initial) and replication of the test results.
Proof of the effective reduction of oxide-of-nitrogen exposure has been furnished under close-to-practical conditions by the PICADA (Photocatalytic Innovative Coverings Applications for Depollution Assessment) Project (supported by the European Union
The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been de ...
and other studies.
Applications
Since the photocatalytic effect is needed only on the surface of a building which is exposed to UV, Tiocem is used primarily in the top layer of a two-layer surface.
The most effective fields for application are:
*Pavement (stones and slabs)
*Roofing tiles
*Noise and screen barriers
*Facades (wall cladding
Cladding is an outer layer of material covering another. It may refer to the following:
*Cladding (boiler), the layer of insulation and outer wrapping around a boiler shell
*Cladding (construction), materials applied to the exterior of buildings
...
)
*Rendering (dry mortar/exterior cement plaster)
*Road construction (e.g. whitetopping)
The abatement of NO2 varies with changing climatic conditions.[ Field tests were carried out with pavements in Bergamo, ]Italy
Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
, on the inside walls of a tunnel in Rome
, established_title = Founded
, established_date = 753 BC
, founder = King Romulus (legendary)
, image_map = Map of comune of Rome (metropolitan city of Capital Rome, region Lazio, Italy).svg
, map_caption ...
[Ramondo, Valeriana (2007), ''"Galleria Umberto I a Roma"''. ''Progretto & Pubblico'' Dicembre 2007, 48-50 (in Italian).] and stucco in Stockholm. In all cases, the requirements of TX Active for NO2 abatement were met.
See also
* Cement
A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mi ...
References
{{Reflist
Cement